Sheet-like waterproofing membrane laminates are well-known for application to concrete and other substrates. These laminates typically comprise a carrier sheet and a pressure sensitive adhesive layer. In many applications, the waterproofing sheet material is applied to a concrete substrate that has already been formed, such as a building foundation. In such a case, the adhesive layer of the membrane is applied against the cured concrete surface. In another technique, the waterproofing membrane is affixed to the concrete form or lagging with the carrier sheet against the lagging and the adhesive portion facing toward the cavity in which the concrete is poured. The adhesive portion of the membrane will adhere to the freshly poured concrete, thus providing a fully adhered waterproofing membrane on the cured concrete surface after the lagging is removed. This technique is sometimes referred to as “blind side” (or pre-applied) waterproofing. A similar process may be used on horizontal surfaces where the membrane is applied to compacted soil or gravel or to a concrete slab, with the adhesive portion facing upward, then casting concrete against the membrane.
In addition to the carrier sheet and pressure sensitive adhesive layer, typical commercial waterproofing membranes include a removable release sheet that is used to prevent the adhesive portion of the membrane from adhering to the carrier sheet or other portion of the membrane when the membrane is rolled up. This release sheet must be removed from the membrane prior to or during installation and disposed in the trash, thus creating environmental waste.
U.S. Pat. No. 3,900,102 (Hurst) discloses one such membrane comprising a polyethylene support sheet, a bituminous adhesive and a releasable siliconized paper for protecting the adhesive. The release paper is removed as the membrane is unrolled and adhered to a building substrate (see Hurst FIG. 4). U.S. Pat. No. 4,751,122 (May) discloses a membrane laminate that includes a sheet-like paper substrate with a release coating (e.g., silicone) on one face and a waterproofing pressure sensitive adhesive on the other face. This membrane also includes a removable strip along the edge which, when removed, permits overlapping seams to adhere. U.S. Pat. No. 4,172,830 (Rosenberg) and U.S. Pat. No. 4,215,160 (Rosenberg) disclose paperless membrane laminates that include a silicone release coating on the outer surface of the carrier sheet to prevent the adhesive layer from adhering to the carrier sheet when the membrane is rolled up. U.S. Pat. No. 5,254,661 (Wilson) discloses a similar type of paperless membrane laminate in which the release coating is a water-based silicone emulsion. During installation, edge portions of the release coating may be removed by wet abrasion to permit adhesion of overlap seams of adjacent membranes.
U.S. Pat. No. 4,994,328 (Cogliano) discloses a waterproofing membrane capable of adhering to freshly poured concrete (i.e., blind-side or pre-applied waterproofing). The membrane has a bituminous adhesive layer that is coated with a non-tacky, water-insoluble polymeric coating such as, for example, a polyvinyl alcohol, silica, and glycerin mixture in a weight ratio of 1:10:0.5. The coating purportedly protects the adhesive layer while permitting a strong adhesive bond to freshly poured concrete. However, the coating can be slippery when wet and, thus, not suitable for foot traffic. U.S. Pat. No. 5,316,848 (Bartlett) discloses a similar blind-side waterproofing membrane that includes a carrier layer, a pressure sensitive adhesive layer, and a protective coating on the adhesive layer, wherein the coating may be selected from various types of polymers, preferably an acrylic-based elastomer, such as styrene butyl acrylate. U.S. Pat. No. 5,496,615 (Bartlett) discloses a similar membrane laminate where the protective coating has a finely divided particulate material, such as sand, calcium carbonate, cement, titanium dioxide, etc., dusted thereon. The Bartlett patents suggest it is preferred that the protective coating is elastomeric (meaning it will stretch to at least twice its original length and return to approximately its original length), has a penetration greater than 30 dmm, and includes carbon black. The exemplified Bartlett membranes exhibit poor bond to concrete after exposure to UV radiation.
U.S. Pat. No. 6,500,520 (Wiercinski) discloses a membrane laminate having a carrier support sheet, an adhesive layer, and embedded on the adhesive layer a layer of granulated inorganic particulates capable of reacting with concrete, such as aluminum oxide trihydrate, silica dioxide, fly ash, blast furnace slag, alkali or alkaline earth metal salts, etc. The particles may be attached to the adhesive layer using a water-soluble material such as ethylene vinyl acetate or polyvinyl alcohol.
Typical commercial waterproofing membranes used for blind-side (or pre-applied) applications include a release sheet and unroll wrong side up with the adhesive portion facing downward. This forces the installer to first unroll then flip over a large, unwieldy membrane prior to installing it. Alternatively, two installers are needed to lift the heavy roll so that it may be unrolled with the correct side facing upward. The need to remove and dispose of a release liner requires additional labor and creates a considerable amount of trash, the disposal of which has significant monetary and environmental costs.
It would be advantageous to provide a waterproofing membrane that binds strongly to concrete cast against its surface, particularly after exposure to sunlight. In addition, it would be advantageous to provide a waterproofing membrane that has an outer surface that will easily tolerate foot traffic, that is not tacky, and that does not wash off, blister or delaminate when exposed to water (i.e., good immersion resistance). It would also be advantageous to provide a waterproofing membrane that has good blocking resistance (i.e., one surface does not adhere to the other surface) so that it does not require a release sheet that must be removed and disposed of at the job site. In addition, it would be advantageous to provide a waterproofing membrane that is right side up (i.e., carrier sheet facing down and adhesive/protective coating facing up) when it is unrolled at the job site. Also, it would be advantageous to provide a waterproofing membrane with an outer layer that is sufficiently hard (lower tack) for good trafficability, yet sufficiently flexible that it will not crack